[blykins]

It's a pretty big deal. You need some special tools...such as some marking paint, and a magnetic base w/ dial caliper. I don't think any documentation comes with the kits, but you can find any Haynes or Chilton's manual that will show you how. What kind of differential do you have currently?

Here's the generalized steps....

Straight axle:

Pull the brakes.
Remove rearend cover.
Drain rearend grease.
Remove large cross pin (there's a small set screw in it also).
Push both axles in towards each other.
Take a pair of needle-nose pliars and a good magnet and remove
the C-clips.
Pull axles.
Unbolt differential bearing caps.
Pull differential and ring gear.
Unbolt ring gear from diff.
Rebolt ring gear to new diff.
Replace carrier bearings.
Probably good idea to replace axle bearings also.
Remount diff in to journals and replace bearing caps.
Reinstall axles...
Push together and reinstall C-clips.
Pull axles away from each other until they hit the clips.
Reinstall cross-bar and screw.
Replace cover and fill with rearend grease.
Replace brakes.

What I didn't tell you was that there are shims that correctly position and locate the differential (with the ring gear bolted to it) so that the gears will mesh together in the right pattern. You can use these shims over again, but it's always a good idea while you have everything apart to check clearances and patterns.

You can set the magnetic base up against the mounting flange of the diff cover and set your dial caliper pointing inside on the ring gear. You can get the right clearances from a repair manual like I mentioned above. You then paint the pinion with the marking paint and rotate the gear pair. There should be a nice clear cigar-shaped mark on the ring gear, where both sets of teeth have meshed. If you've done all this right, the gears will not howl or make any noise.

Just replacing the diff would be easier than changing the gear ratios....you wouldn't have to pull the driveshaft or unbolt the pinion from its journal...or even have the crush sleeve pressed on/off.

This should give you some idea. It's not impossibly hard, but it takes time to do it correctly.

As for IRS, I have no idea how they're setup inside with respect to C-clips and such. I would assume they're the same way since there has to be some way to keep the half-shafts from pulling themselves out. If it is IRS, you should replace all the axle seals as well.

Hope this helps..if you need any other information or details, let me know. I'll try to find them out for you. : )

Brent